Abstract: Apparatus and method for enabling bilateral transmission of digital data between a local area network and telephone company networks employing both analog and digital telephone lines. A modem modulates signals responsive to signals from a local area network representing an outgoing call to form digital telephone signals suitable for transmission by a telephone line and suitable for demodulation by receiving analog modems. A circuit switched time division multiplex bus transmits the digital telephone signals to the telephone line. The modem also demodulates incoming digital telephone signals to form digital network bus signals divided into packets. A packet bus transmits the digital network bus signals to a network interface which processes the signals and transmits them to the local area network.

Abstract: Techniques for generating a line probing signal. The probing signal is comprised of a plurality of different tones, where the tones have a predetermined phase relationship. The signal may be sent over a communication channel, such as a telephone line. By so using the line probing signal, the non-linearity of the electrical characteristics of the telephone line may be measured with increased accuracy.

Abstract: A construction for an interface between a computer and a transmission medium, such as a telephone line. A memory card may be inserted into the computer and interconnected to an interface module, such as a direct access arrangement, which, in turn, is interconnected to a telephone line. The electronic card and interface module each include a connector for transmitting data signals between each other. Each connector includes two rows of contacts. Each contact in the first row is interconnected to a particular contact in the second row. As a result, the electronic card and interface module cannot be attached to each other "upside down." Further, the electronic card and interface module cooperatively define a latch mechanism for releasably holding the two units together. Further, the two units further define a guide assembly for guiding the contacts of the two units into a correct alignment with one another. The latch mechanism and guide assembly add structural integrity to the construction.

Abstract: A module incorporating flash memory chips. An interface enables power down of the chips in response to a power down signal and provides an interrupt signal indicating when all of the ready lines from the memory chips are in a ready state, thereby reducing the need for polling the status registers in the chips.

Abstract: Apparatus and method for managing transmission of digital data between a digital telephone line and a computer network. First and second modems, a telephone control circuit and a network control circuit respond to management instruction signals to execute predetermined management objectives and generate management response signals representing one or more conditions of the first and second modems, telephone control circuit and network control circuit. In response to a single packet of management signals from the network, a management circuit generates the management instruction signals and independently addresses them to one or more of the first and second modems, telephone control circuit and network control circuit.

Abstract: An improved backplane apparatus for transmitting signals to and from a modem system. The modem system includes more than one modem for transmitting data via at least one telephone line and via at least one network. The modem system has a first bus for management signal communication with the modems at a predetermined first data rate, and a second bus for transmitting data between the telephone line and the modems at a predetermined second data rate greater than the first data rate. The modem system also has a third bus for transmitting data between the modems and the network at a predetermined third data rate greater than the second data rate, and a fourth bus for distributing DC power and ground potential. The modem system defines a first impedance for terminating the first bus, a second impedance for terminating the second bus, and a third impedance for terminating the third bus.

Abstract: A modem for connecting data terminal equipment (DTE) to a remote DTE via a general switched telephone network or leased lines at data rates of 300, 1200 and 2400 bps using standard modulation techniques, and additonally providing virtual full duplex transmission capability at 9600 bps using trellis code modulation (TCM). The high-speed 9600 bps path is implemented by asymmetrical frequency division of the available bandwidth into a high speed, wideband forward channel (9600 bps) and a low speed, narrowband backchannel (300 bps). The high speed transmitting channel is assigned to that modem having the greatest data demand and the direction is dynamically reversed whenever the amount of data awaiting transmission over the low speed channel exceeds a predetermined maximum backlog, provided that a direction reversal has not taken place for at least a specified minimum interval during which use of the forward channel is guaranteed.